Not much is known about the history and youth of St. Sixtus, but we do know that he was born in Rome, Italy and ascended to the papacy in 432.

As the 44th Pope, he approved the results of the Council of Ephesus and actively protested against the heresies of Nestorianism and Pelagianism. He restored many Roman basilicas and corresponded frequently with St. Augustine of Hippo.